Arylation of aryllithiums with S-arylphenothiazinium ions for biaryl synthesis

Abstract

Aryllithiums are one of the most common and important aryl nucleophiles; nevertheless, methods for arylation of aryllithums to produce biaryls have been limited. Herein, we report arylation of aryllithiums with...

Sulfur(IV) in Transition-Metal-Free Cross-Couplings for Biaryl Synthesis

“…Kano, Morofuji, and co-workers have developed S -arylphenothiazinium salts 123 as efficient platforms for performing this type of cross-coupling reaction (Scheme ). , This has advanced the field, as it allows the scope to be extended beyond heteroaromatic coupling partners to give the biaryl products 125 . Mechanistic studies supported the intermediacy of a sulfurane intermediate during this reaction.…”

N-Methylphenothiazine S-Oxide Enabled Oxidative C(sp2)–C(sp2) Coupling of Boronic Acids with Organolithiums via Phenothiaziniums

“…We previously reported the arylation of aryllithiums with Sarylphenothiazinium ions for the transition-metal-free synthesis of unsymmetrical biaryls through ligand coupling of sulfuranes, tetracoordinated sulfur(IV) compounds (Figure 1c). 6,7 In this study, S-arylphenothiazinium ions, which were prepared from diaryliodonium salts under harsh reaction conditions, were observed to be specifically suitable for biaryl synthesis. Due to the limited availability of diaryliodonium salts, the scope of biaryl synthesis was confined, and the method was not applied to the synthesis of styrenes and dienes.…”

“…The key to the S–O bond cleavage of PTZSO is that π-electron donation from the lone pair on the nitrogen atom can strongly stabilize the dicationic species. In our previous study, the nitrogen atom in the phenothiazine moiety was found to be necessary for the selective formation of the desired products in the reaction of S -arylphenothiazinium ions with aryllithiums . It is interesting that the nitrogen atom in the phenothiazine moiety is also essential for the oxidative conversion of boronic acids to the corresponding sulfoniums.…”

Recent Progress in C(sp2)–C(sp2) Bond Formation Using Ligand Coupling on Sulfur(IV)

“…Initially, 17 was synthesized from diaryliodonium. 13a A more convenient method for synthesizing 17 from readily available boronic acids was also developed. 13b Moreover, 17 could be used for the O -arylation of alcohols and phenols without transition metals.…”